Saliva is a bodily fluid secreted into the oral cavity by the salivary glands, stimulated by mechanical or chemical stimuli. There are three major pairs of salivary glands: the parotid, submandibular, and sublingual, whose activity is regulated by the autonomic nervous system. Saliva regulates the process of demineralization and promotes remineralization, providing protective effects through its various functions.. One of those functions is the buffering activity of saliva, which regulates its pH and restores it to its baseline levels after it drops, creating acidic conditions. Oral clearance influences the conditions of the oral cavity by mechanically removing and washing away bacteria and sugars which bacteria use in their metabolism. Saliva also contains numerous proteins with antimicrobial properties which participate in the formation of the dental pellicle. Factors that contribute to the development of caries , apart from saliva, include oral microflora as the direct cause of caries, host-related factors and the duration of conditions favorable for caries development. The protective functions of saliva can be reduced or impaired in various conditions that cause hyposalivation. The most common cause is the use of medications, such as antihypertensives, antipsychotics, and antihistamines, while another frequent cause of hyposalivation is Sjögren's syndrome. Patients undergoing radiotherapy for the treatment of head and neck cancer also lose salivary gland function due to the harmful effects of ionizing radiation. Individuals with such saliva secretion disorders are at higher risk of developing caries and require special attention to reduce this risk.